Steam Sti:rilizatium (,k\ W'atkk-Sulujill Mattkr in Soils. 2'ji 



2. On standing for various periods up to three months, without plants 

 growing on thcni, the steamed soils steadily decreased in their content 

 of soluble matter, including ammonia and nitrogenous organic matter. 



3. Amm.onification as well as nitrification (the latter mentioned by 

 Deherain and DeMoussy) were practically non-existent during the three 

 months following steaming. 



4. The time required for the soils to recover from the injurious effects 

 of steaming, as shown by the better growth on the steamed than on the 

 unsteamed soils, was with one exception in the order of their relative 

 productiveness. 



5. Wheat seedlings grown in the aqueous extract of the freshly steamed 

 soil grow less well than those in the extract of the unsteamed soil, but 

 when the extracts were diluted the better growth was made by the seed- 

 lings in the extract of the steamed soil. The results indicate the pro- 

 duction of injurious substances during the steaming process. 



6. Steamed soil on which wheat was grown for three months con- 

 tained decidedly more soluble matter at the end of that time than did 

 that portion of the soil on which no plants were grown, but which stood 

 for the same length of time under similar conditions. 



7. The growth of wheat plants on the steamed soil served to hasten 

 its recovery from the injurious effects of steaming. 



8. The effect of adding an infusion of unsterilized soil to the same 

 soil steamed was to increase greatly the germination of seeds and the 

 early growth of the plants, but to retard later growth, so that the second 

 crop was very much smaller on the steamed soil to which the infusion 

 had been added than on the steamed soil not so treated. 



9. Another effect of the infusion was to hasten the disappearance of 

 total water-soluble matter, but it did not increase nitrification nor did 

 it apparently increase ammonification, at lofst when plants were not 

 growing on the soil. 



